Effects of the novel sodium-dependent phosphate cotransporter 2b inhibitor DZ1462 on hyperphosphatemia in chronic kidney disease.

BACKGROUND: Serum phosphate levels remain insufficiently controlled in chronic kidney disease (CKD) patients, and novel therapeutic strategies are needed. Blocking intestinal phosphate absorption mediated by sodium-dependent phosphate cotransporter type 2b (NPT2b) holds promise as one such strategy. METHODS: The in vitro cellular potency of DZ1462 was evaluated using a radioactive Pi uptake assay on stable Chinese hamster ovary (CHO) cell clones transfected with human NPT2b (hNPT2b) or rat NPT2b (rNPT2b). The ability of DZ1462 to inhibit phosphate absorption was studied in vivo in an acute model after oral bolus challenge with 33PO4 and in an adenine-induced chronic hyperphosphatemia rat model. PK and minitox was also evaluated. RESULTS: The cellular assays with the hNPT2b-CHO and rNPT2b-CHO clones showed that DZ1462 significantly and potently inhibited phosphate uptake. In vivo, in a chronic Pi-fed rat model, DZ1462 effectively inhibited intestinal Pi uptake. In a hyperphosphatemia rat model, DZ1462 significantly inhibited Pi uptake, and DZ1462 in combination with sevelamer had a synergistic effect. The pharmacokinetics (PK) study confirmed that DZ1462 is a gastrointestinal (GI)-restricted compound that can remain in the intestine for a sufficient duration. In addition, DZ1462 also reduced cardiovascular events and ameliorated osteoporosis in a CKD animal model. CONCLUSIONS: This study revealed that a GI-restricted NPT2b inhibitor DZ1462 potently inhibits NPT2b in vitro and blocks intestinal phosphate uptake in multiple animal models with potential to reduce various cardiovascular events in CKD models. Therefore, DZ1462 may be useful to treat renal disease patients who have shown an unsatisfactory response to phosphate binders.

Using halofuginone-silver thermosensitive nanohydrogels with antibacterial and anti-inflammatory properties for healing wounds infected with Staphylococcus aureus.

Contamination by pathogens, such as bacteria, can irritate a wound and prevent its healing, which may affect the physical fitness of the infected person. As such, the development of more novel nano-biomaterials able to cope with the inflammatory reaction to bacterial infection during the wound healing process to accelerate wound healing is required. Herein, a halofuginone­silver nano thermosensitive hydrogel (HTPM&AgNPs-gel) was prepared via a physical swelling method. HTPM&AgNPs-gel was characterized based on thermogravimetric analysis, differential scanning calorimetry, morphology, injectability, and rheological mechanics that reflected its exemplary nature. Moreover, HTPM&AgNPs-gel was further tested for its ability to facilitate healing of skin fibroblasts and exert antibacterial activity. Finally, HTPM&AgNPs-gel was tested for its capacity to accelerate general wound healing and treat bacterially induced wound damage. HTPM&AgNPs-gel appeared spherical under a transmission electron microscope and showed a grid structure under a scanning electron microscope. Additionally, HTPM&AgNPs-gel demonstrated excellent properties, including injectability, temperature-dependent swelling behavior, low loss at high temperatures, and appropriate rheological properties. Further, HTPM&AgNPs-gel was found to effectively promote healing of skin fibroblasts and inhibit the proliferation of Escherichia coli and Staphylococcus aureus. An evaluation of the wound healing efficacy demonstrated that HTPM&AgNPs-gel had a more pronounced ability to facilitate wound repair and antibacterial effects than HTPM-gel or AgNPs-gel alone, and exhibited ideal biocompatibility. Notably, HTPM&AgNPs-gel also inhibited inflammatory responses in the healing process. HTPM&AgNPs-gel exhibited antibacterial, anti-inflammatory, and scar repair features, which remarkably promoted wound healing. These findings indicated that HTPM&AgNPs-gel holds great clinical potential as a promising and valuable wound healing treatment.

Enhancement of sodium taurocholate to the absorption of cefquinome.

The objective of the research was to detect the enhancement effect of sodium taurocholate on the absorption of cefquinome both in Caco-2 cells and rats. The absorption efficiency of cefquinome was determined by high performance liquid chromatography and calculated with apparent permeability coefficients (Papp) after Caco-2 cell monolayers treated odium taurocholate(2 mmol/L) and cefquinome. The results showed that the absorption of cefquinome in Caco-2 cell monolayers was significantly increased with the sodium taurocholate (2mmol/L). Similar results were also detected in the rats orally administrated with 1 mL PBS of cefquinome (20mg/mL) containing different concentration of sodium taurocholate (5 mmol/L, 10mmol/L and 20mmol/L) respectively. Compared with control group, sodium taurocholate at 10 and 20 mmol/L increased the absorption of cefquinome in rats from 0.26±0.04µg/mL to 0.57±0.03µg/mL, 0.78 ±0.07µg/mL respectively. These results indicated that sodium taurocholate could increase the intestinal permeability in a concentration-dependent mode, which will be useful for clinical treatment.

Validation of reference genes for RT-qPCR analysis of CYP4T expression in crucian carp.

Reference genes are commonly used for normalization of target gene expression during RT-qPCR analysis. However, no housekeeping genes or reference genes have been identified to be stable across different tissue types or under different experimental conditions. To identify the most suitable reference genes for RT-qPCR analysis of target gene expression in the hepatopancreas of crucian carp (Carassius auratus) under various conditions (sex, age, water temperature, and drug treatments), seven reference genes, including beta actin (ACTB), beta-2 microglobulin (B2M), embryonic elongation factor-1 alpha (EEF1A), glyceraldehyde phosphate dehydrogenase (GAPDH), alpha tubulin (TUBA), ribosomal protein l8 (RPL8) and glucose-6-phosphate dehydrogenase (G6PDH), were evaluated in this study. The stability and ranking of gene expression were analyzed using three different statistical programs: GeNorm, Normfinder and Bestkeeper. The expression errors associated with selection of the genes were assessed by the relative quantity of CYP4T. The results indicated that all the seven genes exhibited variability under the experimental conditions of this research, and the combination of ACTB/TUBA/EEF1A or of ACTB/EEF1A was the best candidate that raised the accuracy of quantitative analysis of gene expression. The findings highlighted the importance of validation of housekeeping genes for research on gene expression under different conditions of experiment and species.

[Involvement of stress-induced hippocampal synaptic potentiation in the novelty acquisition].

To study the influence of behavioral stress on hippocampal spatial learning and memory, we used the freely moving rats that had undergone chronic implantation of a recording electrode in the hippocampus CA1 region and a bipolar stimulating electrode in the ipsilateral Schaffer collateral-commissural pathway. The field excitatory postsynaptic potentials (fEPSPs) were recorded in the absence of exogenous induction of high-frequency stimulation (HFS) or low-frequency stimulation (LFS) and reflected the effect of stress on the hippocampal spatial learning. And we also investigated the change of hippocampal synaptic plasticity when rats were re-exposed to the same environment at 24 h after novelty acquisition. We found that exploration of a novel environment induced the hippocampal synaptic depression in the rats with stress-adaption, whereas exposure to the novel environment induced the hippocampal synaptic potentiation in the behavioral stress rats. Furthermore, re-exposure to the same environment no longer elicited the hippocampal synaptic potentiation or depression at 24 h after the first novel acquisition in the behavioral stress rats. These results demonstrate that behavioral stress induces the hippocampal synaptic potentiation under novelty acquisition and further damages the hippocampal spatial learning and memory. However, the stress can be adapted by re-exposure to the novelty and thus does not further damage the hippocampal spatial learning and memory.

Effects of fluoroquinolones on CYP4501A and 3A in male broilers.

The inhibitory effects of fluoroquinolones on the enzyme activity, protein levels and mRNA expression of liver cytochrome P450 (CYP) 1A and 3A were investigated in male broiler chicks. Enrofloxacin (20 mg/kg), sarafloxacin (8 mg/kg) and marbofloxacin (5.5 mg/kg) were administrated in drinking water for 7 consecutive days. A cocktail of the probe drugs caffeine and dapsone was used to determine CYP1A and 3A activity. Western blot analysis and real-time PCR were used to determine the effects on protein levels of CYP1A and 3A, and on CYP1A4, 1A5, 3A37 mRNA levels. Enrofloxacin increased the half-life of elimination for both caffeine and dapsone, and decreased expression of CYP1A and 3A protein. Marbofloxacin decreased the metabolism of caffeine and expression of CYP1A protein. However, no change in mRNA expression was observed for any treatment group. This suggested that high doses of enrofloxacin and marbofloxacin, but not sarafloxacin, inhibit CYP in chick liver raising the possibility of drug-drug interaction when using these compounds.

[Dopamine-dependent long-term depression in hippocampus of rat induced by exposure to spatial novelty.].

To study the role of long-term depression (LTD) in the mechanisms of learning and memory in hippocampus of rat, recordings were taken from freely moving animals that had undergone chronic implantation of a recording electrode in the hippocampus CA1 region and a bipolar stimulating electrode in the ipsilateral Schaffer collateral-commissural pathway. The recording electrode was inserted 3.8 mm posterior to bregma and 2.8 mm right of the midline, and the stimulating electrode was inserted 4.8 mm posterior to bregma and 3.8 mm right of the midline via holes drilled through the skull. The entire assembly was connected with a rubber socket on the animal's head and then stabilized with dental cement. The correct placement of the electrodes into the hippocampal CA1 area was confirmed via electrophysiological criteria and postmortem histological analysis. After 2 weeks of surgery recovery, the rats were placed in the familiar recording chamber for 3 days. The field excitatory postsynaptic potentials (fEPSPs) were evoked by stimulating with a square wave constant current pulse of 0.2 ms duration, at a frequency of 0.033 Hz and at a stimulation intensity adjusted to given an fEPSP amplitude of 50% of the maximum, and the baseline of fEPSPs were recorded for 3 days in the familiar recording environment at the same time each day. A novelty environment that was made of clear Perspex (40 cm x 40 cm x 40 cm) was prepared and we examined whether exposure to a novelty spatial environment facilitated the expression of activity-dependent persistent decrease in synaptic transmission (namely LTD) at CA1 synapses in the rat hippocampus. The results showed that brief exposure to a novelty environment for 10 min facilitated the expression of LTD in the hippocampal CA1 area under no other exogenous high- or low-frequency stimulation protocol. This facilitatory effect was dependent on the activation of D1/D5 receptors: the D1/D5 receptors antagonist SCH23390 prevented the decrease of synaptic transmission in the hippocampus during the novelty exploration. These data provided important evidence that LTD may underlie certain forms of learning and memory and that dopamine participates in the synaptic plasticity in the process of hippocampal spatial information storage.

[Cadmium-induced cytotoxicity and intracellular Ca2+ alteration in hepatocytes and protection by selenium].

Cadmium (Cd)-induced cytotoxicity and intracellular Ca2+ alteration ([Ca2+]i) in hepatocytes and intervention with selenium (Se) were studied to discuss mechanism of Cd-induced hepatocyte injury and protective effect by Se. Freshly primary culture hepatocytes isolated from neonatal mice were randomly divided into a normal control group, four treatment groups with cadmium chloride (CdCl2,5,25,100,250 micromol/L, respectively), two treatment groups with sodium selenite (Na2SeO3,10,20 micromol/L, respectively), and eight treatment groups with CdCl2 (5,25,100, 250 micromol/L,respectively) of administered Na2SeO3 (10,20 micromol/L, respectively). Hepatocyte viability and its malondialdehyde (MDA) content as well as lactate dehydrogenase (LDH) activity in cultured medium were assayed, and the intracellular free Ca2+ level ([Ca2+]i) in hepatocytes was detected with laser scanning confocal microscope (LSCM) at 12 h after treatment. The results showed that hepatocyte viability significantly decreased in Cd-exposed groups with dosages, and had no significant differences in Se-treated groups compared with that of control group. Administration of Se increased or obviously raised the viability in Cd-exposed hepatocytes. We observed a dose-dependent increase of LDH activity and significantly higher values in cultured medium of 100 and 250 micromol/L CdC12 groups compared with that in control group,while Se-treated groups had no significant change. LDH activity of administered Se in 25,100,250 micromol/L CdCl2 groups decreased or significant decreased, respectively. Different dosages of Cd induced significant elevation of MDA concentration in hepatocytes, but administration of Se to hepatocytes is incapable of eliciting the same consequences as Cd. 10 and 20 micromol/L Na2SeO3 inhibited or significantly reduced MDA production in hepatocytes induced by 25,100 and 250 micromol/L CdCl2, respectively. [Ca2+]i fluorescence intensity was significantly higher in Cd-exposed hepatocytes than in control cells and showed a dose-dependent manner,however, [Ca2+]i level of administered Se in hepatocytes was not enhanced and near to that of control cells. [Ca2+]i level of administered Se in Cd-exposed hepatocytes greatly decreased compared with Cd-exposed cells and significantly lower values of administered Se in 25 micromol/L CdCl2-exposed hepatocytes were observed and near to that of control cells. These results suggest that Cd induce cytotoxicity and damage as well as [Ca2+]i elevation in hepatocytes. Se can relieve the process of cytotoxicity and damage by intervening lipid peroxidation,improving and protecting [Ca2+]i homeostasis in Cd-induced hepatocytes.